Tim Krul believes Newcastle's January spending spree has revitalised the Magpies as they continue to distance themselves from the Premier League relegation zone.
Krul, 24, is also confident the new arrivals can bolster Newcastle's Europa League campaign, which continues against Metalist Kharkiv on Thursday, although Mathieu Debuchy and Yoan Gouffran are ineligible for the competition.
Debuchy and Sissoko have had an immediate impact for the Toon and Krul claims they have already created a positive atmosphere at St James' Park, with two wins from their last three league outings.
"We have had a really hard time during the first half of the season, but with these new faces coming in, it gives us a massive boost and a lot of confidence," he said. "We have still got a lot of hard games to play, but we can go into those games with a lot of confidence.
"They have been fantastic. Normally you see with new players, they take a bit of time to settle. But these lads, from the moment they walked into the club, they have been great for us."
Krul admits to having limited knowledge of Newcastle's Ukrainian opponents, but is well prepared for the return leg having played there for Netherlands at Euro 2012.
"Funnily enough, I know a lot about the stadium because we played all our three group game in the Euros there," he said. "We have had, of course, a team meeting and we know everything about the players now, but before, I didn't know much."
Metalist are yet to resume their season after going on a winter break in early December and have not played a competitive match in over two months
But Newcastle boss Alan Pardew is not willing to take any cautions ahead of the match, preparing his side for the fluid attack of a large South American contingent.
"It's not ideal for them, but on the other and, it can work well," he said. "They will obviously be very fresh and very motivated for this game, and that can hide a number of sins.
"They have a large influx of South American players, who give the team a real characteristic of technique, and that's probably what we are going to have to come up against.
"They are very good at keeping the ball and keeping it away from us, and will probably take our tempo out of the game. That's their strength, and on the break, they are fast, so we need to be on our guard. As Juventus proved on Tuesday night at Celtic, you have to be very clever in how you attack."